So, I've been looking at starting Synergy so I can work on some PUP gear from it however, I'm looking at the recipe, and the wiki page on Synergy, and I don't fully understand, if I need all the crafts myself, or if I only need the Synergy craft leveled and my party members can have the other skills

Synergy takes into account all of the crafts of people of your party and uses only the highest ones.

If an item requires 100 smithing, 100 leather, and 50 synergy. You need someone in your party with 100 smithing and another with 100 leather. There is no gap limit, so you can make a level 50 synergy item at 0 skill.

You, yourself, need 0 of those skills, but if you want something made from synergy, you must do the starting quest in Metalworks otherwise you can not use the furnance, preventing you from starting the process.

EDIT: The synergy skill of each person is taken into account individually. You just need someone that is able to make the item (and have him do all the work). You can have people gather together with lesser synergy skill and try to work together as a party, but unless everyone knows about synergy, that can be difficult to do.

I can't confirm it but i've been seeing/hearing a lot from my friends that the rate of skill ups from synergy may have been nerfed (at leasted useing the etching weapons trick). I went from 20 - 28 today and it seemed to take an extremly large amount of fewell then usual (usually seeing .6 skill ups out of 100 fewell). 4 of my friends have also thought skill ups seemed to have slowed down since update. It may have been just a coincidence though unless anyone else has noticed (we think it's only the etching weapon trick but none of us have tried other recipes lately)

Yeah on average it took me about an hour to gain one level while skilling up on etching. Also after 35 I didn't get any more skill ups from it at all so I made my fisherman's smock and dinged 36 doing that before moving on to Mythril Nuggets to ding 50.

By then the update happened and I got some gold leaf x4 and vitriol to ding 60 a few days ago.